A South Korea-based company under fire for failing to deliver any of its 75 double-decker coaches to the commuter rail on time is making progress on its $190 million contract with the state, and three of the cars will be in service in April, with 15 expect­ed to be running by September, the head of the MBTA said Monday.

“We promise we’re going to deliver,” Beverly Scott, general manager of the MBTA, said in a phone interview.

Earlier in the day, Scott visited the Philadelphia plant of Hyundai Rotem, the company building the coaches, and said she was “impressed with the organ­ization.”

“I’m really glad we’re turning the corner,” she said.

A company spokesman could not be reached for comment Monday.

Along with the cars that are expected to be running by September, the entire fleet will be ready for the commuter rail in 2014, Scott said.

“We’re not going to compromise quality,” she said. “You can tell there is a commitment from Hyundai.”

Mass transit push

Scott’s comments differed markedly from December, when state transit officials threatened to end the contract. The chief financial officer of the Massachusetts Bay Transportation Authority wrote in a letter to the company at the time that “this seriously troubled procurement is at a point of crisis.”

When the contract was awarded in early 2008, the first four cars were scheduled to ­arrive by October 2010, and all 75 were supposed to be carrying commuters in and out of Boston by the end of 2012. ­Instead, the first four coaches did not reach the MBTA for testing until last fall.

Scott said Monday that the company has committed more funding, materials, and workers to the plant in recent months. She also said that production delays in projects of similar scope are common.

“I wish I could tell you otherwise,” said Scott, a 35-year public transit veteran who previously led the transit system in Atlanta. She was selected for the MBTA job last September.

Hyundai Rotem made a bold entrance into the US market a decade ago with attractive promises, well-placed connections, and prices that beat experienced competitors.

Some in the industry considered it a risky bet, given that Hyundai Rotem had yet to open an assembly plant on American soil, a requirement under federal law. At the time, the company had not yet demonstrated experience negotiating the stricter safety standards and other require­ments that have bedeviled several large international corporations trying to break ­into the US transit and passenger rail market.

Scott’s visit to Philadelphia came after company officials met with her and other T officials in Boston last week.

Scott pledged Monday to keep a close eye on production.

“You never put them on ­automatic pilot,” she said, “so this won’t be the last time that I’ll be down there. . . . The proof is in the pudding, at the end of the day.”

Eric Moskowitz of the Globe staff contributed to this report. Travis Andersen can be reached at tandersen@globe.com. Follow him on Twitter @TAGlobe.